1. Field of the Invention
The present invention relates to a dishwasher, and more particularly, to a dishwasher capable of cleaning a screen filter thereof, and a controlling method of the dishwasher.
2. Description of the Related Art
A dishwasher is a home appliance that sprays wash liquid (that flows by means of a wash pump) from nozzles onto upper and lower racks, to wash dishes placed on the racks.
Specifically, a dishwasher includes a tub forming a wash compartment, a dish rack disposed inside the tub for storing dishes, a spray nozzle for spraying wash liquid onto the surface of dishes, and a sump installed at the bottom of the tub for storing wash liquid.
Installed inside the sump are a wash pump that pumps wash liquid under high pressure and a wash motor for driving the wash pump.
The dishwasher also includes a water guide connected to the sump to provide a passage for the flow of wash liquid, an upper spray arm branching off from a portion of the water guide to be disposed in the approximate central portion of the tub, and a top nozzle formed at the top portion inside the tub.
In a dishwasher according to the related art, high-pressure wash liquid sprayed from the upper spray arm and top nozzle causes food residue and other impurities on the surfaces of dishes to be removed and fall to the floor of the tub, whereupon the fallen impurities enter the sump.
A self-cleaning filter for filtering impurities is installed at the top of the sump, to prevent impurities of a large size from entering the inside of the sump.
A disposer is installed within the sump to grind impurities that enter the sump into small particles, and a screen filter is provided to prevent the small particles ground by the disposer from entering the wash pump.
In this way, clogging of the passages (through which wash liquid flows to the spray arm and nozzle) by the impurities is prevented by grinding the impurities that enter the sump.
In order to prevent the holes in the screen filter from being clogged by the impurities, the disposer rotates at around 3300-3400 rpm.
However, when the disposer rotates during dishwasher operation, a grinding noise created by the disposer rotating against the screen filter can be disconcerting to a user.
Also, rotation of the disposer may be insufficient to remove impurity particles stuck in the screen filter, so that the impurities accumulate on the screen filter and hinder the flow of wash liquid.